Question: Ashley is 18 years older than Omar. Sixteen years ago, Ashley was 3 times as old as Omar. How old is Omar now?
Explanation: We can use the given information to write down two equations that describe the ages of Ashley and Omar. Let Ashley's current age be $a$ and Omar's current age be $o$ The information in the first sentence can be expressed in the following equation: $a = o + 18$ Sixteen years ago, Ashley was $a - 16$ years old, and Omar was $o - 16$ years old. The information in the second sentence can be expressed in the following equation: $a - 16 = 3(o - 16)$ Now we have two independent equations, and we can solve for our two unknowns. Because we are looking for $o$ , it might be easiest to use our first equation for $a$ and substitute it into our second equation. Our first equation is: $a = o + 18$ . Substituting this into our second equation, we get the equation: $(o + 18)$ $-$ $16 = 3(o - 16)$ which combines the information about $o$ from both of our original equations. Simplifying both sides of this equation, we get: $o + 2 = 3 o - 48$ Solving for $o$ , we get: $2 o = 50$ $o = 25$.